Building block



FIG. 1 is a front perspective view of the building block, showing the new design;

FIG. 2 is a front elevational view of the building block thereof;

FIG. 3 is a rear elevational view of the building block thereof;

FIG. 4 is a left side elevational view of the building block thereof;

FIG. 5 is a right side elevational view of the building block thereof;

FIG. 6 is a top plan view of the building block thereof; and,

FIG. 7 is a bottom plan view of the building block thereof. 

CLAIM The ornamental design for a building block, as shown and described. 